Typically, solenoid valves are electromechanically operated valves having two main parts; the solenoid and the valve. The solenoid converts electro-magnetic energy into mechanical energy which, in turn, opens or closes the valve mechanically. Solenoid valves are used in a wide variety of applications, including in switchable valvetrains of internal combustion engines. Solenoid valves are disclosed in U.S. Pat. No. 7,137,411, and U.S. Pat. No. 6,367,434 wherein the solenoid valve comprises an electromagnet having a hollow cylindrical magnet housing, at least one coil winding and an armature, and a valve member having a hollow cylindrical valve housing for receiving a spool valve which is displaceable relative to the valve housing by the armature of the electromagnet.
So called “fast switching solenoids” operate by the same principle as solenoid valves generally. PCT application PCT/EP2012/062080 describes such a fast switching solenoid, comprising a magnetic coil surrounding an armature and magnetic core, the armature connected to a armature pin, extending through the magnetic core and attached to a valve body. A perforated housing member surrounds the valve assembly, the assembly comprising a valve spring, spring seat, valve body, valve plate on which the valve body seats and a spring retainer.
In fast switching solenoid valves, a seal can be used between the magnet core, valve body and the spring seat in order to ensure isolation between the high pressure chamber, around the periphery of the perforated housing, and middle pressure chamber, at the bottom of the valve, adjacent the spring retainer. Where misalignment occurs between the valve body and the valve plate in the housing, the seal can be compressed or permanently compacted during operation of the valve body during actuation. This seal may also contribute to increased friction of the system, depending on the temperature and pressure of the oil, negatively influencing switching performance of the valve.
The valve plate is typically pressed into the housing, requiring a tight tolerance between the valve plate and the housing and sorting of parts during assembly.